# -*- coding: utf-8 -*-

# Define here the models for your spider middleware
#
# See documentation in:
# https://docs.scrapy.org/en/latest/topics/spider-middleware.html

import time
import random

import scrapy
from scrapy import signals
from selenium import webdriver

from .user_agents import agents




class TzktSpiderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the spider middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_spider_input(self, response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.

        # Should return None or raise an exception.
        return None

    def process_spider_output(self, response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.

        # Must return an iterable of Request, dict or Item objects.
        for i in result:
            yield i

    def process_spider_exception(self, response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.

        # Should return either None or an iterable of Request, dict
        # or Item objects.
        pass

    def process_start_requests(self, start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.

        # Must return only requests (not items).
        for r in start_requests:
            yield r

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)


class TzktDownloaderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_request(self, request, spider):
        # Called for each request that goes through the downloader
        # middleware.

        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called
        return None

    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.

        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response

    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.

        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)







"""
自定义中间间
"""
# 随机生产 用户代理 中间件
class RandomUserAgentMiddleware(object):
    def process_request(self, request, spider):
        # 1. 使用随机函数, 从序列中获取UA数据
        agent = random.choice(agents)
        # 2. 将数据赋值给请求头部.
        request.headers["User-Agent"] = agent
        return None


# 动态调用谷歌浏览器驱动;
class DriverMiddleware(object):

    def process_request(self,request,spider):
        """
        通过selenium 对request发起请求;
        :param request:
        :param spider:
        :return:
        """

        # 打开浏览器
        self.driver = webdriver.Chrome()
        # 判断当前request是否需要调用selenium
        if request.meta.get('driver',False):
            # 条件成立，说明driver的值为Ture，否则为 False
            self.driver.get(request.url)
            # 延时一下，因为代码运行比较快，浏览器打开加载速度比较慢；需要等待一下获取数据;
            time.sleep(1.5)
            # 获取 selenium 中的源码
            html = self.driver.page_source
            # 驱动退出 当前窗口，;
            self.driver.quit()

            # 返回Response对象
            return scrapy.http.HtmlResponse(url=request.url,body=html,encoding='utf-8',request=request)


# 动态调用 无头浏览器 浏览器驱动;
class PhantomMiddleware(object):

    def process_request(self,request,spider):
        """
        通过selenium 对request发起请求;
        :param request:
        :param spider:
        :return:
        """
        print('无头浏览器 启动,Phantom ',)

        # 打开浏览器
        self.driver = webdriver.PhantomJS()
        # 判断当前request是否需要调用selenium
        if request.meta.get('driver',False):
            # 条件成立，说明driver的值为Ture，否则为 False
            self.driver.get(request.url)
            # 延时一下，因为代码运行比较快，浏览器打开加载速度比较慢；需要等待一下获取数据;
            time.sleep(1.5)
            # 获取 selenium 中的源码
            html = self.driver.page_source
            # 驱动退出 当前窗口，;
            self.driver.quit()

            # 返回Response对象
            return scrapy.http.HtmlResponse(url=request.url,body=html,encoding='utf-8',request=request)
















